Epoxy resin composition

ABSTRACT

Disclosed is an epoxy resin composition suitable for sealing a semiconductor, comprising an epoxy resin (A), a hardener (B), an inorganic filler (C), and a phosphoric acid ester compound (D), an amount of the inorganic filler (C) contained being more than 80% by weight relative to the composition. A semiconductor sealing epoxy resin composition excellent in flame retardancy, formability, reliability and solder heat resistance is obtained without an essential need to use a halogen-based flame retardant or an antimony-based flame retardant.

TECHNICAL FIELD

The present invention relates to an epoxy resin composition excellent inflame retardancy, high-temperature reliability and solder heatresistance and, more particularly, to a semiconductor sealing epoxyresin composition and a semiconductor device.

BACKGROUND ART

As for a method for sealing electronic circuit portions, such assemiconductor devices, a sealing method using a sealing resin containingan epoxy rein, a hardening agent and an inorganic filler is mainlyemployed, in view of cost effectiveness, productivity, and balance inproperties. Due to the recent trend toward less thickness and higherpackaging density of semiconductor devices, there are increasing demandsfor high solder heat resistance, high-temperature reliability, humidityresistance reliability and the like of semiconductors. Correspondingly,requirements for sealing resins have been escalating.

For safety ensurance, the UL standards impose a requirement thatelectronic component parts, such as semiconductor devices, be providedwith flame retardancy. Accordingly, conventional sealing resins contain,as a flame retarding agent, halide-based flame retardant agents such asa brominated epoxy resin and, as a flame retarding assistant, antimonycompounds such as antimony trioxide.

With recently growing concerns about environmental issues, problems orchallenges have been pointed out in respect to various compounds used asflame retarding agents in semiconductor sealing resins.

There is a problem in that when a semiconductor device sealed by anepoxy rein composition containing a halide flame retardant agent isplaced in a high temperature environment, the reliability of thesemiconductor decreases.

Furthermore, concerns have risen over troublesome processes required forresin wastes if antimony compounds are contained in the such resins.

There have been demands for further improvements in the solder heatresistance and high-temperature reliability of semiconductor devices andthe package filling characteristics for the sealing of semiconductors.

It is an object of the present invention to provide an epoxy reincomposition excellent in flame retardancy, high-temperature reliability,solder heat resistance and formability represented by package fillingcharacteristics without essentially requiring a halide-based flameretarding agent or an antimony compound, which are conventional flameretarding agents, and to provide an epoxy resin composition thatimproves the humidity resistance reliability if that property isrequired.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention is:

(1) an epoxy resin composition comprising an epoxy resin (A), a hardener(B), an inorganic filler (C), and a phosphoric acid ester compound (D),an amount of the inorganic filler (C) contained being 80% by weightrelative to the composition, and more particularly,

(2) an epoxy resin composition according to (1), wherein a proportion ofthe epoxy rein (A) in the epoxy resin composition is 0.05-15% by weight,and a proportion of the hardener (B) is such that a chemical equivalentratio of the hardening functional group of the component (B) to theepoxy groups of the component (A) is 0.5-1.5, and a proportion of thephosphoric acid ester compound (D) is such that the phosphorous atoms ofthe phosphoric acid ester compound (D) is 0.01-10% by weight relative tothe components excluding the inorganic filler,

(3) an epoxy resin composition according to (1) or (2), wherein aphosphorous atom of the phosphoric acid ester compound has a valency offive,

(4) an epoxy resin composition as described in any one of (1)-(3),wherein the phosphoric acid ester compound has an aromatic group,

(5) an epoxy resin composition as described in any one of (1)-(4),wherein the phosphoric acid ester compound (D) has in its molecule astructure of the following chemical formula (I): ##STR1## (in thefomula, X represents at least one aromatic group, and may be the same ordifferent)

(6) an epoxy resin composition as described in any one of (1)-(5),wherein the epoxy resin composition contains an ion capturing agent,

(7) an epoxy resin composition as described in (6), wherein the ioncapturing agent is a hydrotalcite-based compound,

(8) an epoxy resin composition as described in any one of (1)-(7),wherein the epoxy resin (A) comprises as an essential element a biphenyltype epoxy component having a structure of the following chemicalformula (II): ##STR2## (where R1-R8 in the formula represent hydrogenatoms, alkyl groups having a carbon number of 1-4, or halogen atoms),

(9) an epoxy resin composition as described in any one of (1)-(8),wherein the hardener comprises as an essential component a phenolcompound (VI) represented by the following formula: ##STR3## (wherein mis an integer equal to or greater than 0, X is a bivalent aromatic groupand may be the same or different, and Y is a univalent or bivalentaromatic group and may be the same or different),

(10) an epoxy resin composition as described in any one of (1)-(9),wherein at least 50% by weight of the phosphoric acid ester compound hasa molecular weight of 300 or greater,

(11) an epoxy resin composition as described in any one of (1)-(10),characterized in that an amount of the inorganic filler (C) is 85-98% byweight relative to the resin composition,

(12) an epoxy resin composition as described in any one of (1)-(11),wherein an oxygen index of the composition after being hardened is equalto or higher than 42%,

(13) an epoxy resin composition as described in any one of (1)-(12),wherein the epoxy resin composition is applicable to semiconductorsealing, and

(14) a semiconductor device wherein a semiconductor element is sealed byan epoxy resin composition as described in (13).

Further, the method of the invention is:

(15) a method for producing an epoxy resin composition characterized bymelting and mixing an epoxy resin (A), a hardener (B), an inorganicfiller (C), and a phosphoric acid ester compound (D) (wherein an amountof the inorganic filler (C) compounded is at least 80% by weightrelative to the composition),

(16) a method for producing a semiconductor sealing epoxy resincomposition characterized by melting and mixing an epoxy resin (A), ahardener (B), an inorganic filler (C), a phosphoric acid ester compound(D) and an ion capturing agent (wherein an amount of the inorganicfiller (C) compounded is at least 80% by weight relative to thecomposition), and

(17) a method for producing a semiconductor sealing epoxy resincomposition as described in (16), wherein the ion capturing agent is ahydrotalcite-based compound.

In the composition of the present invention, by compounding at least 80wt. % inorganic filler (C) and compounding a phosphoric acid ester, aflame retardancy is provided and, further, formability represented byfilling characteristics is improved. Furthermore, if a semiconductordevice is formed by sealing a semiconductor element with the compositionof the present invention, an excellent humidity resistance reliabilityand an excellent solder heat resistance are achieved. Further, bycompounding a hydrotalcite-based compound, the humidity resistancereliability is improved.

BEST MODES FOR CARRYING OUT THE INVENTION

The present invention will be described in detail below.

The epoxy resin (A) in the present invention is not particularly limitedas long as it has a plurality of epoxy groups in its molecule. Specificexamples of the epoxy resin (A) are, for example, cresol novolac typeepoxy resin, phenol novolac type epoxy resin, biphenyl type epoxy resin,bisphenol A type epoxy resin, bisphenol F type epoxy resin, linearaliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin,spiro ring-containing epoxy resin, halogenated epoxy resin, and thelike.

Among these epoxy resins (A), an epoxy resin particularly preferable foruse in the present invention, in view of excellence in solder heatresistance, is one that contains as an essential component a biphenyltype epoxy resin having a skeleton represented by the following generalformula (II): ##STR4## (wherein R1-R8 in the formula represent the sameor different ones of hydrogen atoms, alkyl groups having a carbon numberof 1-4, and halogen atoms).

The epoxy resin (A) preferably contains a biphenyl type epoxy reinhaving a skeleton represented by the foregoing chemical formula (I) inan amount of 50% by weight or more, and, more preferably, 70% by weightor more.

Preferable examples of the epoxy resin skeleton represented by theforegoing formula (I) are:

4,4'-bis(2,3-epoxy-propoxy)biphenyl;

4,4'-bis(2,3-epoxy-propoxy)-3,3',5,5'tetramethylbipheny l;

4,4'-bis(2,3-epoxy-propoxy)-3,3',5,5'-tetramethyl-2-chl orobiphenyl;

4,4'-bis (2,3-epoxy-propoxy)-3,3',5,5'-tetramethyl-2-bro mobiphenyl;

4,4'-bis (2,3-epoxy-propoxy)-3,3',5,5'-tetraethylbipheny l;

4,4'-bis (2,3-epoxy-propoxy)-3,3',5,5'-tetrabutylbipheny l;

4,4'-bis (2,3-epoxy-propoxy)biphenyl;

4,4'-bis (2,3-epoxy-propoxy)-3,3',5,5'-tetramethylbiphen yl; and thelike. Any of these may be used alone or in a mixed system, achievingsufficient advantages. The aforementioned epoxy resin includes, withinits scope, polymers formed by opening the rings of epoxy groups.

In the present invention, the amount of the epoxy resin (A) compoundedis normally 0.05-15% by weight, more preferably, 2-15% by weight,further more preferably 2-9% by weight, in the epoxy resin compound, inview of formability and adhesion property. If the amount is too small,the formability or adhesion property becomes insufficient. If the amountis too large, the coefficient of linear expansion of the hardenedmaterial becomes large, with a tendency that reduction of stress in thehardened material will become difficult.

The hardener (B) in the present invention is not particularly limited aslong as it reacts with the epoxy resin (A) for hardening. Normally,compounds having phenolic hydroxyl groups, compound having acidanhydrides, or amines may preferably be used. Examples of such acompound, that is, a compound having two or more phenolic hydroxylgroups in its molecule, are, for example, phenol novolac resin, cresolnovolac resin, phenol-p-xylylene copolymer (generally termed phenolaralkyl resin) represented by formula (VI) below, various novolac resinssynthesized from bisphenol A, resorcin or the like, various polyhydricphenols such as tris(hydroxyphenyl)methane, dihydrobiphenyl and thelike, polyvinyl phenol and ##STR5## (wherein m is an integer equal to orgreater than 0, X is a bivalent aromatic group and may be the same ordifferent, and Y is a univalent or bivalent aromatic group and may bethe same or different).

Examples of the compound having an acid anhydride are maleic anhydride,phthalic anhydride, pyromellitic anhydride, and the like. Examples ofthe amines include, but are not limited to, aromatic amines, such asmetaphenylenediamine, di(aminophenyl)methane (generally termeddiaminodiphenyl methane), diaminodiphenyl sulfone and the like. Forsemiconductor sealing, phenyl-based hardeners may preferably be used inview of heat resistance, humidity resistance and storability. In someapplications, two or more kinds of hardeners may be used together.

The phenol-based hardener preferably contains a phenol aralkyl resinhaving a structure represented by formula (III) below in view of anexcellent solder heat resistance and a low water absorption of aresulting semiconductor device. The amount thereof compounded ispreferably at least 50% of the hardener: ##STR6## (wherein R representsa hydrogen atom or an organic group and may be the same or different, Rpreferably being a hydrogen atom or a methyl group, and m is an integerequal to or greater than 0).

It is preferable that a structure represented by the foregoing formulawherein m is equal to or less than 3 be contained in an amount of 90% byweight or less.

The amount of the hardener (B) compounded in the present invention isnormally 0.5-20% by weight, preferably 1-10% by weight, more preferably1-9% by weight, relative to the entire resin composition. Preferably,the compound ratio between the hardener (B) and the epoxy resin (A) issuch that the chemical equivalent amount ratio of the hardeningfunctional groups of (B) to the epoxy groups of (A) is within a range of0.5-1.5, preferably 0.8-1.2, in view of mechanical characteristics andhumidity resistance reliability.

In the present invention, it is possible to use a hardening catalyst inorder to accelerate the hardening reaction between the epoxy resin (A)and the hardener (B). The hardening catalyst is not particularly limitedas long as it accelerates the hardening reaction. Examples of thehardening catalyst are imidazol compounds such as 2-methylimidazol2,4-dimethylimidazol, 2-etyl-4-methylimidazol, 2-phenylimidazol,2-phenyl-4-methylimidazol, 2-heptadecylimidazol and the like, tertiaryamine compounds such as triethylamine, benzyldimethylamine,α-mehtylbenzyldimethylamine, 2-(dimethylaminomethyl)phenol,2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diaza-bicyclo(5,4,0)undeccen-7 and the like, organic metal compounds such as zirconiumtetramethoxide, zirconium tetrapropoxide, tetrakis(acetylaceto)zirconium, tri(acetylaceto)aluminum and the like, organic phosphinecompounds such as triphenyl phosphine, trimethyl phosphine, triethylphosphine, tributyl phosphine, tri(p-methylphenyl)phosphine,tri(nonylphenyl)phosphine and the like. Among these, organic phosphinecompounds are preferably used in view of humidity resistance. Thesehardening catalysts may be used in combination of two or more kindsdepending on applications. The amount thereof added is preferably withina range of 0.1-10 parts by weight relative to 100 parts by weight of theepoxy resin (A).

Examples of the inorganic filler (C) are amorphous silica, crystallinesilica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay,talc, calcium silicate, titanium oxide, asbestos, glass fiber and thelike. Among these, amorphous silica is preferably used since it has agreat effect on reduction of the coefficient of linear expansion and iseffective to reduce stress. Amorphous silica may be produced in anydesired method, for example, a method wherein crystalline silica ismelted, a method wherein amorphous silica is synthesized from variousmaterials, and the like.

The configuration and particle diameter of the amorphous silica in thepresent invention are not particularly limited. However, in view offluidity, it is preferable that the amorphous silica have sphericalparticles of an average particle diameter equal to or greater than 3 μmbut less than or equal to 40 μm, and be used in the inorganic filler inan amount of 60% by weight or more. More preferably, the amount ofamorphous silica in the inorganic filler is 90% by weight or more.

The average particle diameter herein means a particle diameter (mediandiameter) with an accumulated weight of 50%. In the present invention,the proportion of the inorganic filler (C) is preferably 80-98% byweight and, more preferably, 85-98% by weight relative to the entireresin composition, in view of flame retardancy, formability and lowstress.

The phosphoric acid ester compound, that is, the component (D) in thepresent invention, refers to compounds having bonds of "P--O--R" (Rbeing an organic group) as chemical structures. Normally, phosphoricacid ester compounds wherein the phosphorus atoms have a valency ofthree or five are used. As for phosphoric acid ester compounds havingtrivalent phosphorus atoms, there are phosphite compounds, phosphonitecompounds, and phosphinite compounds. As for phosphoric acid estercompounds having pentavalent phosphorus atoms, there are phosphatecompounds, phosphonate compounds, and phosphinate compounds. Amongthese, phosphoric acid ester having pentavalent phosphorus atoms arepreferably used in view of storage stability and flame retardancy.

Among these phosphoric acid ester compounds, compounds having aromaticgroups as organic groups forming esters are preferred in view of flameretardancy, humidity resistance reliability and solder heat resistance.

Examples of such phosphoric acid ester compounds are triphenylphosphate, resorcinol bis(diphenol) phosphate, 2-ethylhexyldiphenylphosphate, and other compounds described later.

Further, it is preferable that a skeleton represented by formula (I)below is contained in the molecule: ##STR7## (wherein X represents anaromatic group having a valency of one or greater, and may be the sameor different).

More specifically, compounds represented by formulas (IV) and (V) areindicated: ##STR8## wherein (wherein R represents the same or differentones of a hydrogen atom or an alkyl group having a carbon number of 1-5;Ar represents the same or different aromatic groups, Y represents adirect bond, an alkylene group; a phenylene group, --S--, --SO₂ -- or--CO--; Ar represents the same or different phenyl groups or phenylgroups substituted with an organic group; k and m are integers equal toor greater than 0 but less than or equal to 2, and k+m is an integerequal to or greater than 0 but less than or equal to 2; n is an integerequal to or greater than 0). Among such compounds, compounds having thestructure of IV are preferably used.

The phosphoric acid ester compound in the present invention may also bea mixture of compounds having different chemical structures or a mixtureof compounds having different molecular weights. As for the amount ofthe phosphoric acid ester compound added, the lower limit amount of thephosphorus atoms of the phosphoric acid ester compound is preferably0.01% by weight, more preferably 0.1% by weight, and the upper limitamount thereof is preferably 10% by weight, more preferably 5% byweight, relative to the amount of components of the epoxy resincomposition excluding the inorganic filler, in view of flame retardancy,solder heat resistance and humidity resistance reliability.

It is preferred that phosphoric acid ester compound having molecularweights of 300 or greater, preferably 500 or greater, be contained inthe phosphoric acid ester in an amount of 50% by weight or more, in viewof humidity resistance and solder heat resistance. In the composition ofthe present invention, it is also possible to compound a phosphoric acidester having trivalent phosphorus atoms and form a phosphoric acid esterhaving pentavalent phosphorus atoms through oxidation in thecomposition, achieving substantially the same advantages. The phosphoricacid ester compound may also be a compound obtained by hydrolyzing esterlinkages and binding other phosphorus atoms thereto so as to provideP--O--P linkages, that is, a condensate.

If a further enhanced humidity stability is required for a semiconductordevice, it is preferable to compound an ion capturing agent into theresin composition of the present invention. The ion capturing agent isan agent having a function of capturing an ion. Examples of such anagent are ion exchangers, and hydrotalcite-based compounds.

The ion exchanger means a substance having a function of ion exchange,for example, a substance having a function wherein in contact with asolution having ions, ions leave the substance into the solution whileions are taken up into the substance from the solution.

The hydrotalcite-based compound refers generally to nonstoichiometriccomplex metal compounds represented by formula (VII) below, andcompounds obtained by firing the former compounds so that water andA^(n-) groups are partially or completely removed.

     M.sup.2+.sub.1-α M.sup.3+.sub.α (OH).sub.2 !.sup.α+  A.sup.n-.sub.α/n ·mH.sub.2 O!.sup.α-(VII)

In the formula, M²⁺ means a bivalent positive ion of metal, forexamples, bivalent positive ions of magnesium, manganese, iron, cobalt,nickel, and copper.

M³⁺ 0 means a trivalent positive ion of metal, for example, trivalentpositive ions of aluminum, iron, chrome, cobalt and indium.

A^(n-) means a negative ion having a valency of n, for example, OH⁻,Br⁻, F⁻, Cl⁻, NO3⁻, CO₃ ²⁻, SO₄ ⁻, Fe(CN)₆ ³⁻, CHCOO⁻, C₆ H₄ (OH)COO⁻,tartaric acid ion, oxalic acid ion, salicylic acid ion, and the like.

α is normally greater than 0 but less than or equal to 0.33 in order toprovide a structure having an ion capturing characteristic, and mrepresents a number equal or greater than 0.

Normally, magnesium ion may be used as M²⁺, and aluminum ion may be usedas M³⁺, and CO₃ ²⁻ may be used as A^(n-).

Preferred specific examples of the hydrotalcite-based compoundsrepresented by (VII) are Mg₄.5 Al₂ (OH)₁₃ CO₃ ·3.5H₂ O, Mg₄.5 Al₂ (OH)₁₃CO₃, Mg₅ Al₁.5 (OH)₁₆ CO₃ ·4H₂ O, Mg₆ Al₂ (OH)₁₆ CO₃, and the like.Preferred specific examples of compounds obtained by removing water andnegative ions from the compounds represented by formula (VII) are Mg₀.65Al₀.35 O₁.175, Mg₀.7 Al₀.3 O₁.15, Mg₀.75 Al₀.3 O₁.125, Mg₀.8 Al₀.3 O₁.1,and the like. Hydrotalcite-based compounds from which water and negativeions have been removed may be obtained by firing hydrotalcite-basedcompound represented by (VII) at 400-900° C. and, preferably, 500-700°C.

If a hydrotalcite-based compound is compounded in the present invention,the amount thereof added is 0.01-5% by weight, preferably 0.02-3% byweight, more preferably 0.03-1% by weight. If the amount is too small,no effect is obtained by the addition. If it is too large, the solderheat resistance tends to decrease.

It is preferable that silane coupling agent be compounded into the epoxyresin composition of the present invention. As a silane coupling agent,compounds wherein silicon atoms directly are bonded with a an organicgroup such as hydrolytic group amino groups, halogen atoms, alkoxygroups and the like, and partial hydrolytic condensates thereof arenormally used. As a hydrolytic group, an alkoxy group, in particular,methoxy group and ethoxy group, may preferably be used. As an organicgroup, hydrocarbon groups or hydrocarbon groups substituted by nitrogenatoms, oxygen atoms, halogen atoms, sulfur atoms and the like, may beused. Silane coupling agents having organic groups having amino groups,and silane coupling agents having organic groups having epoxy groups arepreferably used. Further, silane coupling agents having secondary aminogroups are preferred.

It is also possible to add to the epoxy resin composition of the presentinvention substances other than described above, for example, colorantssuch as carbon black, iron oxide and the like, elastomers such assilicone rubber, olefin-based copolymers, modified nitrile rubber,modified polybutadiene rubber, modified silicone oil and the like,thermoplastic resins such as polyethylene and the like, long-chain fattyacid, metal salts of long-chain fatty acids, esters of long-chain fattyacids, amides of long-chain fatty acids, mold release agents such asparaffin wax and the like, cross linking agents such as organicperoxides, as desired.

In the present invention, it is also possible to compound flameretardant agents such as halogen compounds including halogenated epoxyresin, and various flame retarding assistants such as antimony trioxide.However, since these substances have a tendency to reduce thereliability of a semiconductor device, it is preferred that the amountsof halogen atoms and antimony atoms in the resin composition be,respectively, 0.2% by weight or less, further, 0.1% by weight or less,still further, 0.01% by weight or less. It is further preferred thatsubstantially no halogen atoms and substantially no antimony atoms becompounded.

Furthermore, in the epoxy resin composition of the present invention, itis preferred that the oxygen index after the hardening of the epoxyresin be 42% or higher, in view of flame retardancy, high-temperaturereliability and formability.

In the epoxy resin composition of the present invention, it is preferredthat after the aforementioned materials are mixed, the mixture be meltedand kneaded. The epoxy resin composition may be produced by melting andkneading by using a known kneading method, for example, a Banbury mixer,a kneader, a roll, a single or double-screw extruder, a co-kneader, andthe like. The melting temperature is preferably within a range of60-130° C. Further, by sealing a semiconductor with the epoxy resincomposition of the present invention, a semiconductor device is formed.

The semiconductor device herein refers to electronic circuits(integrated circuits) produced by integrating and wiring semiconductorelements, such as transistors, diodes, resistors, capacitors and thelike, on substrates and, more widely, to electronic parts sealed by theepoxy resin composition of the present invention.

EXAMPLES

The present invention will be described specifically with reference toExamples. In Examples, % is based on weight.

EXAMPLES, COMPARATIVE EXAMPLES

Components shown in Table 1 were dry-blended by a mixer at compositionpercentages shown in Table 2. After the mixtures were heated and kneadedfor five minutes by a mixing roll at a roll surface temperature of 90°C., the mixtures were cooled and ground to produce semiconductor sealingepoxy resins composition.

Using the resin compositions, moldings were formed by a low-pressuretransfer molding method in conditions of 175° C. and 2 minutes for curetime. After post-cure was performed at 180° C. for 5 hours, propertiesof the resin compositions were evaluated by the following propertymeasurement methods.

Solder Heat Resistance: Twenty 160-pin QFPs (quad flat packages) havinga chip size of 12×12 mm carrying dummy semiconductors withvapor-deposited Al wirings were formed. After being subjected tomoistening at 85° C./85%RT for a predetermined length of time, the QFPswere heated in an IR re-flow furnace at a maximum temperature of 245° C.The number of external crack incidents were determined.

Water Absorption: After the same 160-pin QFPs as used in the solder heatresistance test were subjected to moistening at 85° C./85%RT, the waterabsorption of the resin compositions were measured.

High-Temperature Reliability: Using 16-pin DIPs (dual in-line packages)carrying dummy semiconductors thereon, high-temperature reliability at200° C. was evaluated. The length of time before the accumulated failurerate became 63% was determined as high-temperature property life time.

Flame Retardancy Test: Flame test pieces of 5"×1/2"×1/16" were moldedand post-cured. Flame retardancy thereof was evaluated in accordancewith the UL94 standards.

Oxygen Index: Test pieces of 5"×1/2"×1/8" were molded and post-cured. Inaccordance with JIS K7201, the volume concentrations of gasses at limitsof flammability were determined.

    Oxygen index (%)= oxygen!/( oxygen!+ nitrogen!)

PKG Filling Characteristics (Package Filling Characteristics): After160-pin QFPs for use in the solder heat resistance test were formed, theQFPs were observed visually and microscopically to checkpresence/absence of unfilling or void.

Results are shown in Table 3.

                  TABLE 1    ______________________________________                                     Amount                                     added                                     (part(s)                                     by    Name       Description           weight)    ______________________________________    Epoxy resin    I          Ortho-cresol novolac resin of an epoxy                                     *               equivalent amount of 200    II         4,4'-bis(2,3-epoxy-propoxy)-3,3',5,5'-                                     *               tetramethylbiphenyl    Hardener    I          Phenol novolac resin of a hydroxyl                                     *               group equivalent amount of 107    II         Phenol compound represented by formula                                     *               E below    Inorganic filler               Amorphous silica having an average                                     *               particle diameter of 10 μm    Frame retardant    I          Phosphoric acid ester compound                                     *               represented by formula A below    II         Phosphoric acid ester compound                                     *               represented by formula B below    III        Phosphoric acid ester compound                                     *               represented by formula C below    IV         Phosphoric acid ester compound                                     *               represented by formula D below    V          Triphenyl phosphate   *    VI         Bisphenol A type resin of an epoxy                                     *               equivalent amount of 400, having a               bromine content of 50% by weight    Flame retarding               Antimony trioxide     *    assistant    Hardening  Triphenylphosphine    0.1    accelerator    Silane coupling               N-phenylaminopropyltrimethoxysilane                                     1.0    agent    Colorant   Carbon black          0.2    Mold release agent               Carnauba wax          0.3    Hydrotalcite               DHT4H by Kyowa Kagaku Kogyo                                     *    compound    ______________________________________     *Amounts added are indicated in Table 2.     ##STR9##

                                      TABLE 2    __________________________________________________________________________    Amount of      Amount of                     Amount of    epoxy resin added                   hardener added                            Amount of                                     Flame retardant                                                 flame retarding                                                          Hydrotal cite-    (part(s) by weight)                   (part(s) by weight)                            filler added                                        Amount added                                                 assistant added                                                          base compound    I         II   I   II   (part(s) by weight)                                     Type                                        (part(s) by weight)                                                 (part(s) by                                                          (part(s) by    __________________________________________________________________________                                                          weight)    Example 1          0.0 7.9  0.0 7.0  80.0     I  3.5      0        0    Example 2          0.0 6.0  0.0 4.9  85.0     I  2.5      0        0    Example 3          2.6 2.6  0.0 4.7  87.0     I  1.5      0        0    Example 4          0.0 6.1  1.9 1.9  87.0     I  1.5      0        0    Example 5          0.0 5.5  0.0 4.4  87.0     I  1.5      0        0    Example 6          0.0 5.0  0.0 4.0  89.0     I  0.4      0        0    Example 7          0.0 5.5  0.0 4.4  87.0     I  1.5      0        0    Example 8          0.0 5.5  0.0 4.4  87.0     II 1.5      0        0    Example 9          0.0 5.5  0.0 4.4  87.0     III                                        1.5      0        0    Example 10          0.0 5.5  0.0 4.4  87.0     IV 1.5      0        0    Example 11          0.0 5.5  0.0 4.4  87.0     I  1.5      0        0.1    Example 12          0.0 4.3  0.0 3.9  90.0     I  0.3      0        0    Example 13          0.0 5.5  0.0 4.4  87.0     V  1.5      0        0    Comparative          0.0 9.0  0.0 7.9  78.0     I  3.5      0        0    Example 1    Comparative          0.0 6.3  0.0 5.1  87.0     -- --       0        0    Example 2    Comparative          0.0 6.8  0.0 5.6  85.0     VI 0.5      0.5      0    Example 3    Comparative          0.0 6.3  0.0 5.1  87.0     -- --       0        0.1    Example 4    __________________________________________________________________________

                                      TABLE 3    __________________________________________________________________________                Flame High-temperature                               PKG     Solder                                            Water           Oxygen                retardancy                      reliability                               filling heat absorption           index (%)                (UL94)                      (h)      characteristics                                       resistance                                            (%)    __________________________________________________________________________    Example 1           45   V-0   400      good    0/20 0.28    Example 2           44   V-0   500      good    0/20 0.21    Example 3           47   V-0   >500     good    0/20 0.19    Example 4           48   V-0   >500     good    0/20 0.19    Example 5           50   V-0   >500     good    0/20 0.15    Example 6           52   V-0   >500     good    0/20 0.13    Example 7           50   V-0   >500     good    0/20 0.15    Example 8           50   V-0   >500     good    0/20 0.15    Example 9           50   V-0   >500     good    0/20 0.15    Example 10           49   V-0   >500     good    0/20 0.17    Example 11           50   V-0   >500     good    0/20 0.16    Example 12           55   V-0   >500     good    0/20 0.12    Example 13           50   V-0   400      good    5/20 0.16    Comparative           41   V-1   200      good    10/20                                            0.31    Example 1    Comparative           40   V-out 400      Void    0/20 0.13    Example 2    Comparative           49   V-0   130      Void    2/20 0.25    Example 3    Comparative           39   V-out 400      Void    0/20 0.13    Example 4    __________________________________________________________________________

As shown in Table 3, epoxy resin compositions according to the presentinvention were excellent in flame retardancy, solder heat resistance,high-temperature reliability and package filling characteristics.

A few of the aforementioned compositions were selected and subjected tohumidity resistance reliability test (PCBT property life timemeasurement). In the measurement method, 16-pin DIPs (dual in-linepackages) were used for evaluation of disconnections under conditions of140° C., 85%RT and DC20V applied. The length of time before theaccumulated failure (disconnection) rate became 63% was determined.

Results are shown in Table 4.

                  TABLE 4    ______________________________________                  PCBT characteristic life time (h)    ______________________________________    Example 5       80    Example 11      250    Comparative Example 2                    100    Comparative Example 4                    250    ______________________________________

Table 4 shows that compounding the hydrotalcite-based compound achieveda greater improvement in the humidity resistance reliability in thecompositions containing phosphoric acid ester compound than in thecompositions containing no phosphoric acid ester compound.

INDUSTRIAL APPLICABILITY

A semiconductor sealing epoxy resin composition excellent in flameretardancy, formability, reliability and solder heat resistance isobtained without an essential need to use a halogen-based flameretarding agent or an antimony-based flame retarding agent. It becomespossible to improve the performance of semiconductors obtained as aresult of use of the epoxy resin composition.

We claim:
 1. An epoxy resin composition comprising an epoxy resin (A), ahardener (B), an inorganic filler (C), and a phosphoric acid estercompound (D), an amount of the inorganic filler (C) contained beinggreater than 80% by weight relative to the composition.
 2. An epoxyresin composition according to claim 1, wherein a proportion of theepoxy rein (A) in the epoxy resin composition is 0.05-15% by weight, anda proportion of the hardener (B) is such that a chemical equivalentratio of the hardening functional group of the component (B) to theepoxy groups of the component (A) is 0.5-1.5, and a proportion of thephosphoric acid ester compound (D) is such that the phosphorous atoms ofthe phosphoric acid ester compound (D) is 0.01-10% by weight relative tothe components excluding the inorganic filler.
 3. An epoxy resincomposition according to claim 1 or 2, wherein a phosphorous atom of thephosphoric acid ester compound has a valency of five.
 4. An epoxy resincomposition according to any one of claims 1-3, wherein the phosphoricacid ester compound has an aromatic group.
 5. An epoxy resin compositionaccording to claim 1, wherein the phosphoric acid ester compound (D) hasin its molecule a structure of the following chemical formula (I):##STR10## wherein X represents at least one aromatic group, and may bethe same or different.
 6. An epoxy resin composition according to claim1, wherein the epoxy resin composition further comprises an ioncapturing agent.
 7. An epoxy resin composition according to claim 6,wherein the ion capturing agent is a hydrotalcite-based compound.
 8. Anepoxy resin composition according to claim 1, wherein at least 50% byweight of the phosphoric acid ester compound has a molecular weight of300 or greater.
 9. An epoxy resin composition according to claim 1wherein the amount of the inorganic filler (C) is 85-98% by weightrelative to the resin composition.
 10. An epoxy resin compositionaccording to claim 1, wherein the composition after being hardened hasan oxygen index equal to or higher than 42%.
 11. An epoxy resincomposition according to claim 1, wherein the epoxy resin composition isapplicable to semiconductor sealing.
 12. A semiconductor device whereina semiconductor element is sealed by an epoxy resin composition definedin claim
 11. 13. A method for producing an epoxy resin compositioncharacterized by melting and mixing an epoxy resin (A), a hardener (B),an inorganic filler (C), and a phosphoric acid ester compound (D)(wherein an amount of the inorganic filler (C) compounded is at least80% by weight relative to the composition).
 14. A method for producing asemiconductor sealing epoxy resin composition characterized by meltingand mixing an epoxy resin (A), a hardener (B), an inorganic filler (C),a phosphoric acid ester compound (D) and an ion capturing agent (whereinan amount of the inorganic filler (C) compounded is at least 80% byweight relative to the composition).
 15. A method for producing asemiconductor sealing epoxy resin composition according to claim 14,wherein the ion capturing agent is a hydrotalcite-based compound.